


Humans Suck and Mermen Don't Exist

by EEhtirsA_the_other_one



Category: Shingeki no Kyojin | Attack on Titan
Genre: Bottom Eren Yeager, Eren is a merman, Fish parts, Hanji is a creeper, Levi wants to forget everything, M/M, Top Levi (Shingeki no Kyojin), more tags to come
Language: English
Status: In-Progress
Published: 2015-07-29
Updated: 2016-12-28
Packaged: 2018-04-11 20:41:03
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 13,166
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4451609
Author URL: https://archiveofourown.org/users/EEhtirsA_the_other_one/pseuds/EEhtirsA_the_other_one
Summary: <blockquote class="userstuff">
              <p>Can Eren rip this midget's legs off please?<br/>That bug eyed thing is staring at him and he can't tell if it's a guy or a girl.<br/>The bottom of the pool is literally the only place he's safe from the fire stick.<br/>This guy won't stop sniffing his hair and he just wants to go home.</p>
            </blockquote>





	1. Fish Out of Water

**Summary for the Chapter:**

> When fishing gets you more than you wanted.  
> Since when does that happen?

**Notes for the Chapter:**

> AO3 is weird.

Eren couldn’t remember how far back his fascination with the human world went, but at this point it no longer mattered. His avid interest with the land bound creatures had dulled in the past few years as his interest in survival far surpassed his childhood fantasies. He would often recall how he and Armin would speak of swimming all the way to the surface, seeing the true sun and breathing the air above the water like his ancestors once had. He sometimes wished he could still employ such dreams, especially now that his world had turned so dark.

The need to survive had turned his childhood obsession into his saving grace, but sadly enough, had forced him to take a stance of disinterest on the subject of humans. He had been a collector of human artifacts when he was young, and he would often swim through old boat wreckage with his siblings, Armin and Mikasa, hoping to find treasures hidden among the piles of decaying wood. They never found anything most of the time, as traders and treasure hunters picked over mostly everything. Sometimes though, they would find something special. Once, he brought home am old leather thing, hoping his father would know what it was. He told him that it was a shoe, an object that humans used to protect their feet. To this day, Eren had no idea what feet were, or how shoes even functioned, as his father had been unwilling to elaborate.

At the time, the lack of information only piqued his interest even more, but now he wished he knew less about the human race than he did. His trips to ship ruins were no longer an act of childish curiosity, but of necessity. What he found in the human waste could be sold, making a profit that allowed Eren to fulfill his share of work to support the meagre household he shared with his siblings. The wonderment of his fellow merfolk was all that made ends meet, and more often than not, many would repurpose human trinkets into something useful in their watery world. 

Eren’s sister Mikasa made a more decent living, weaving baskets and bags from the thick seaweed that clung to the ocean floor. He wasn’t quite sure if she necessarily enjoyed the profession, but she was willing to do the labor intensive work if it contributed to their semblance of comfort. Armin did odd jobs for however much people were willing to pay, and sometimes Eren and Mikasa wouldn’t see him for days at a time. In the end, they got food on the table, and that was enough for all of them. The only problem that any of them had was that what Eren was doing wasn’t entirely legal. Sure, he could get an artifacts license, but that takes years of schooling, and school was expensive. No one would take Eren in any other kind of work, so this is what he had to lower himself to. It wouldn’t be the first time he had done something illegal in order to survive. He got money for his trouble, so no one really complained, but there would always be the risk of the Military Police arresting him. Then he would be helping no one, so he was cautious in every way.

Eren deftly swam between the splintered wreckage of a ship’s hull and the coral reef it had crashed into. His trained eyes scanned the thing from top to bottom. Not much here. He had doubted that he would be able to find anything. This ship sat on the edge of a common travel rout, and it had been picked over dozens of times before being abandoned because of increased human activity in the area. Eren scowled at the thought. The tribe would have to pack up and move on again within the next week. The humans were moving in on them once again, and Eren and everyone else would be forced to move into deeper waters to reek refuge from the human's fishing nets and diving ships. Eren and his fellow Merfolk had been on the move for many years now, trying to avoid the humans and their ocean industry as they moved further and further away from the shore, breaching the borders of their ancient society and decimating their population. 

The humans had dominated the land, and now they were stretching their domain to even the deepest waters, forcing merfolk into the darkest parts of the ocean in order to survive. many tribes had disappeared into the depths, never to be seen again. There were rumors of a new generation of merfolk that had adapted to survive in the freezing waters in the deepest parts of the ocean. It was said that they had pale skin, lidless eyes that were pure white due to the darkness, and possessed spines and poisonous bites that allowed them to fight against the monsters of the deep. Eren hoped they were just rumors, exaggerations that had developed among the tribes when they spoke of the last merfolk stronghold in the Bermuda Triangle. The mermen and maids that lived there were pale and held up in their ways of royal tradition. They were said to be a fierce and unforgiving lot of people who could pull entire ships into the depths of the ocean in just moments. Some said they ate human flesh as a rare delicacy there. Eren believed it all to be conjecture and lies made up by those in the tribes who's only dream had been to enter the walled city that was hostile to outsiders. There were rumors about humans as well, rumors that stated that the humans had created ships that could dive deep under the ocean, and that they were manned with dozens of humans and weapons of war that could destroy anything at the press of a button. Rumors like that instilled a sense of fear in people, and it kept them moving forward, moving into deeper and darker waters. Just five years ago, Eren had lived in warm coastal waters, where the sun shone brightly through the surface. He enjoyed the company of the reef fish, and the chances of meeting a friendly human were far more plausible. Now, he was far from land, dredging up a living in the darkness; and still he continued to sink deeper. The humans had wronged him in more ways than one, and if he ever met a human today, he would probably drown it.

Eren spent the next half hour exploring the wreckage, only finding a few useless baubles, not worth the effort of trying to sell. He felt some comfort at the realization that many humans had probably died in the crash. Legend has it that this particular ship had been set upon the reef by lord Poseidon himself when humans attempted to hunt mermaids for their tears. Serves the humans right.

After wandering around the wreckage for another hour, Eren decided to go ahead and head home so that he could help Armin and Mikasa pack up. They would be moving out two days from now, and the three of them still had a lot to do. He swam lazily back through the wreckage, admiring the coral and seaweed that had begun to feed on the rotted wood. Just as Eren emerged from the wreckage of the ship, a swarm of fish swam by, their synchronized movements making the water distort around them. They seemed to be in a hurry and Eren watched as many other fish straggled behind the swarm. He had to scoff at the collective panic that the fish were forced to suffer. Just like him, they were forced to revert to instinct in order to survive, however if even a single one of them panicked or felt threatened, then the entire mass would respond with equal levels of panic and fear. The whole swarm would move and respond according to the will of a single member. They all protected each other inside the mass, but outside of it, they were forced to face reality or die. Most died. For many, the real world was cruel and unforgiving. Those who relied on the mass only allowed their instincts to go so far. They never truly accounted for their own safety, and in the end, the world swallowed them whole.

Eren could not help but compare himself to the stragglers, except he did not struggle in his individuality. He welcomed his mostly independent life, and did rather well in supporting himself and Mikasa and Armin. In the end though, he was truly bound to a mass of people. It was too dangerous for small groups to travel the world's oceans alone. They had to move in large groups with a few hundred members each. Big enough to hold its own against a threat, small enough to go undetected by humans.

The swarm disappeared into the distance, and Eren looked back to the direction from which they came, only for a shiver of dread to make its way down his spine. He didn't stop to think, he only responded. He turned towards where the swarm had fled, and he too joined the straggling fish in their desperate escape. It was a net. A giant human fishing net. It moved quickly, its gaping maw wide open to reveal dozens of fish already trapped within it.

He began to swim up, finding that the sides of the net were far too wide out for him to escape by swimming long-ways. He couldn't swim fast enough. It was right on top of him. Eren tried to dodge around the top lip of the net, and barley made it, but a loop in the rope snagged onto his tail, jerking him away from his ascent and into the flow of the net. Eren cursed as he was flipped backwards, his tail twisting awkwardly in the net. His arms were forced over his head by the strength of the current, and he struggled to bring them to his side, where his knife rested in its pouch. Eren glanced down just in time to witness the fleeing school of fish being swallowed into the net. The humans were getting smarter, learning the swimming patterns of the schools.

Eren gritted his teeth as the bottom of the net began to angle upwards. The humans were pulling in their catch. Eren had only moments. He was hanging upside down now, his body suspended in the water, away from the net, even as it angled quickly upwards. He reached his arm up to his waist and grasped his knife, pulling it from its sheathe. His back bumped against the side of the net, and Eren could see the top of the net breaking water. This was not good. Eren dug his fingers into the net, trying to pull his body back up to his tail. A quarter of the net was above water now. He grasped the rope around his tail and began to saw with his other hand. The position he was in hurt terribly. It was hard to breathe with his hip digging into his ribcage, but he forced his focus in on the rope. Only half of the net remained in the water. The knife wasn't working. The ropes weren't damaged at all. It was like he was a single barnacle clinging to the tail end of a whale. He began to panic now as the net right above his tail surfaced, and before he knew it, his tail, chest, shoulders, and head had breached the water. He clawed at the rope desperately as the last of the net was lifted from the water.

This couldn't be happening. This could not. Be. Happening. He began hyperventilating, and then he began coughing as he realized that he couldn't breathe. The gills on his neck flared as he tried to breathe in water, but there was no water, only air. There were shouts, and Eren looked over to see people running around on the deck of a huge human ship. Many stopped and pointed in his direction. They were going to catch him. He was going to die, and the entire populace in the water under him would be compromised because of it. He had to escape. Eren released the net, and his body hung limp from the link. He tried to collect some of the water falling from the net and shovel the water onto his gills, but it was a fruitless effort. Eren gasped again and again as he and the net were dropped onto the deck of the human ship unceremoniously. The net fell on top of him, along with tons of flapping fish, who were struggling to breathe as much as he was. He had to escape. He glanced to where his tail was still caught in the net. He could escape if he sacrificed one of his fins. It wouldn't be too traumatic of a loss. He could grow the fin back. There were more shouts, and Eren blanched as he realized that the humans were looking for him among the piles of fish. It was now or never.

Eren steeled himself, and then jerked his tail forward. Pain unlike anything he had ever experienced before filled him, and he couldn't help the cry that escaped his lips. Tears welled in his eyes, and he blinked them away to inspect his tail. The right fin was completely torn off, barely hanging on by a tiny strip, but his tail was free. Despite the pain, he grinned in triumph, and didn't stop to think as he pulled himself towards the edge of the deck. His gills flared, and he gasped for breath desperately as he clawed for freedom. His tail dragged uselessly behind him, and he struggled as the weight seemed to increase each second. There was an opening on the deck railings, big enough for him to slip right through. If he could just make it there. Just as his had reached for the railing, gasping for breath, strong hands grasped his tail, and suddenly he was being pulled backwards.

All at once, the edge of the ship disappeared from his view, and he didn’t even have the strength to fight back as he realized that he was about to pass out. Eren tried to knock the hands away with his tail, but his body was going numb. He heard curses and shouts behind him, more hands grabbed his body. They pulled him away from the water, away from freedom, and Eren could only close his eyes in defeat as he finally passed out, his gills closing and folding into the skin of his neck. After that, there was only darkness.

 

 

Part 2: You’re kidding, right?

Levi Ackerman had never been a morning person. Anyone who had ever spent a morning with him knew this to be true. He was unapproachable until at least six thirty, and he had better have had his coffee by then or he would be in a bad mood all day. Well, worse than usual. Yet somehow, he was woken at the ass of dawn by an incessant racket at his front door. At first he had turned over in his bed and hoped it was just a dream, but it soon proved to be very real when a rock came hurdling through his bedroom window. He jumped out of bed and bolted for the window, swiping up the rock as he did so.

He pulled back the curtains and rolled up the blinds to find none other than Hanji waving her arms around and screaming like a lunatic on his front lawn. Levi cursed as he rolled up the window. “This had better be good shitty-glasses! You owe me a new window!” The crazed woman didn’t seem to hear Levi as she hopped up and down, screaming something intelligible. Her face was flushed, and her hair was disheveled, her goggles falling onto her forehead. The woman was wearing her lab coat, which meant that she either went to the lab extremely early this morning or never left it last light. Levi was sure it was the latter. Hanji didn’t seem like she was going to shut up any time soon, and Levi could see some of the neighbors peeking outside to see what was with all the commotion.

Levi sighed. It was way too early for this. He was sure he would have a headache before he even arrived at the lab, which is where he was sure Hanji would drag him off to. Levi bounced the decent sized stone in his hand and decided that there was only one possible thing he could do with it. He threw it at Hanji. It hit her in the head. The scientist went down hard, and the screaming went along with her. Levi nodded, satisfied that the scientist would be otherwise occupied for at least the next half hour. He closed the window, drew the blinds, and closed the curtains, scoffing at a small cloud of dust that now filtered through the air.

He dressed quickly and then made his way into the kitchen. He set the coffee to brew and then set about making his breakfast. He decided on something simple, as he doubted he would have the chance to enjoy a proper meal with Hanji now passed out on his front lawn. He knew she wouldn’t stay that way for long. Sure enough, he had just finished his bagel when there was a knock at the door. Levi rubbed his eyes tiredly before he made his way to the front door. Two cups of coffee still wouldn’t prepare him to deal with Hanji this early in the morning. The woman was too high energy, able to run for days on end before finally collapsing behind a desk somewhere in the lab. She rarely ever showered, and, much to Levi’s disgust had no restraints when it came to physical contact with other people. More than once, Levi had been itching for a shower from just being in the scientist’s presence. Levi had to wonder who thought it would be funny to stick a germaphobe and a spit-shine onto the same team, and make them partners no less. The woman was a genius, but Levi could hardly stand her.

Levi took a deep breath, steeling himself before swiftly opening the door. It was not Hanji at the door.

“E-Erwin?” Levi questioned, completely caught off guard by the man’s appearance.Erwin was already dressed for work, his slacks crisp and pressed, and his tie adjusted perfectly under his shirt collar. He too was wearing his lab coat, and it was only then that Levi noticed an uncharacteristic gleam of amusement in the older man’s eye.

“You have to give it to Hanji,” he began, a small grin adorning his lips. “She can get people out of bed in the morning.” Levi only grunted in response. The initial surprise of Erwin’s visit had worn off, and now Levi was wondering what the hell was going on. Oluo and Petra were just behind Erwin, picking up an unconscious Hanji from the yard and carrying her to the car. Looks like the whole lab team is out here, he thought. What next, will the new intern Jean show up, reveal he was a centaur and then ride off into the sunrise? Levi could take no more surprises this morning. He turned his attention back to Erwin.

“Want to explain why Hanji was screaming like a loon on my front lawn?” Erwin only smiled and handed Levi a manila folder.

“We have a new subject to investigate,” he said, his eyes gleaming in anticipation. Levi glanced through the papers quickly, and he didn’t even finish reading them before he scoffed and closed the folder. This was just insulting. “If you’re going to prank someone, you might want to use a more believable excuse to get them out of their house.”

Erwin didn’t even bat an eye as Levi scowled up at him. “Levi, there is a time for practical jokes, and there is a time for discovery, and I feel that pushing you onto the proverbial banana peel is the least of my concerns.”

Levi breathed heavily through his nose. It was too. Damn. Early. “I’m not in the mood for any of your games Erwin! You seriously expect me to believe that we have a mermaid sitting in the laboratory.”

“… It’s technically a merman from what we can tell, but, yes.”

Levi slapped himself in the face with the folder. Erwin huffed. “Levi, if I could have taken pictures of the thing I would have, but for now this discovery will remain a secret. We can’t go gallivanting all over the internet and the media with this story until we’re sure. Otherwise people would think we’re crazy.” Levi decided not to comment on that and remained silent. Honestly at this point, he wouldn’t mind if Jean came running around the corner as a full-fledged majestic stallion. Such an event would do nothing to add to the abnormality of the day so far. Erwin continued to stand on Levi’s porch, having no intention to depart until Levi agreed to come as well. Oluo and Petra waited rather impatiently by the car, clearly ready to depart as well. Levi sighed before reluctantly grabbing his keys and his lab coat. Screw it, he thought. Might as well get this over with. Little did he know that this was only the beginning.


	2. Fucking Fantastic

**Summary for the Chapter:**

> Levi meets a merman, and Hanji is still a creeper.

**Notes for the Chapter:**

> Well, here's the next chapter. I'm really going to start falling behind, as the next three months are some of the busiest in my life. I'm talking about band camp. I am in a leadership position, and we practice from 8am to 8pm five days of the week (except Wednesdays, which are 8am to 5pm). I'll try to stay consistent, but no promises. I have other stories that are posted on other sites that I must also commit to.

Levi honestly didn’t know what he expected. When he was informed that there was a merman swimming around in one of the aquarium exhibits at the research center, he wanted to believe that it was just some huge, elaborate prank. He wanted the whole thing to blow over, and then move on as if it never happened.

He most certainly was not expecting this.

Hanji was revived on the trip to the research center, and Levi was later informed that she cried the whole time for not getting to deliver the news. When they arrived, Hanji took the lead and began explaining how they found the mermen.

Apparently a commercial fishing vessel had hauled in a net full of fish along with the merman, whose tail had been caught on the net. They saw him hanging from the net and thought he was an unlucky diver, until they saw the giant green tail.

 They dumped it on deck and had to scramble to keep it from jumping back into the water. It wounded itself in its escape and nearly died because it couldn’t breathe. They managed to keep it alive by dumping buckets of water in its head until they wrangled it into an old water heater.

This was almost a week ago, and when the vessel came to port, the captain came straight to the AMRC (Aquatic Mammal Research Center).

Erwin and Hanji had been the only ones present at the time, and they were more than happy to get the merman off of his hands.

Everyone had decided then and there that it would be best if the merman’s existence was kept a secret for now.

Erwin managed to get the merman into an exhibit tank, and that was where the thing was now. Erwin had wanted to get his marine mammal expert on the scene before they attempted any sort of interaction with the merman, much to Hanji’s disappointment.

Everything after that, Levi was fully up to speed on.

He was still struggling to process some of it.

Erwin had ushered him into the aquarium far too quickly, and all of them had stood and waited by the glass for what seemed like ages. Nothing happened.

Levi had had quite enough at that point, and had been ready to turn and leave when suddenly something crashed against the glass.

Levi looked up, and what he saw there should have been impossible.

It was a boy, a teenager. His eyes were huge, the most intense greenish-blue color that Levi had ever seen in his life. The boy’s eyes were angry, shadowed by his brown hair as he banged a fist against the glass.

His chest was bare, and his muscles were well built, strong shoulders flowing into a sturdy, yet narrow frame. Levi wanted there to be legs past the boy’s waist, but there was no chance.

Tanned skin flowed into deep green and gold scales that shimmered beautifully in the light. The long tail tapered elegantly, with only a dorsal fin branching out from its smooth scaled surface. The tail ended with a strong set of fins that had well-built muscles surrounding them. One of the fins had been ripped off though, and rather recently by the looks of it.

The merman slammed his hand on the glass again, and four slits on either side of his neck flared, the fleshy underside becoming visible for a moment before they faded into nonexistence, settling down easily with the skin of his neck. Gills.

The merman swam around in a circle, agitated. He was not happy with being thrown into the large exhibit and seemed to be struggling with his wounded fin.

Levi could only stare. This should have been impossible. Mermaids were legends, stories made up by fishermen with their tales of monsters, heroism, and sea beauties.

Yet here he was, staring at the stuff of legends that was now occupying a giant fish tank in a modern day human city.

It was almost laughable how a creature, who's existence has been heavily disputed for centuries, could just be swept up in a fishing net and thrown into the laps of modern day marine biologists.

The merman circled back around, becoming more and more tense at every second that passed.

Levi placed his hand against the glass, just in time to feel the vibrations of sound as the merman screamed in anger. Levi couldn't hear it, but the sound shook the glass of the aquarium, and he could see the frustration being let out of the merman as he screamed his anger away.

The vibrations faded, and the mermen clenched his fists, his body tensing.

Suddenly, he hurdled his body forwards, jetting through the water like a bullet from a barrel. He turned his body, and the merman's shoulder rammed into the glass with a resounding crunch. Shouts of surprise echoed through the hallway.

The merman pulled away, revealing a web of cracked glass radiating outwards from the point of impact.

Levi's eyes widened, the silver orbs making contact with the merman's green ones, which shone with determination.

The merman smirked, his chest heaving from the exertion. He backed away slowly, and it was only then that Levi realized he was reeling back for another attack, ready to slam his entire body into the glass.

Levi didn't stop to think. He turned and sprinted down the hallway, even as Erwin and the others called after him.

This was not going to happen. If the stupid merman broke the glass, then the contents of  the aquarium's  largest exhibit  would be spilled all over the hall floor. Levi did not want to have to explain that one, not to mention the thousands of dollars it would cost them in repairs and for care of the displaced fish that also inhabit the exhibit.

Levi skidded down the hallways, cursing as he slammed through the maintenance doors. He sprinted up a flight of stairs as he pulled a set of keys from his pocket.

He couldn't get the key in the lock fast enough, and after what felt like forever, he was through the doors that led to the tank maintenance room. It was here that the workers made sure the tank was in working order, and it was the access point for people to get inside and clean the tanks.

There was a whole wall dedicated to the storage of scuba gear, and it was that wall that Levi sprinted towards. He didn't have time to get suited up, so he grabbed an oxygen tank, goggles, flippers, and some other necessary items.

He quickly stripped out of his shirt and pants, throwing them off to the side as he pulled the tank straps over his shoulders and secured them. It took him practically no time at all to get on all of his gear.

He ran into a separate room and grabbed another piece of equipment that he hoped would not be necessary, but it was better to be safe than sorry. If the merman tried to kill him, it would be all too easy for him to pull the breather out of Levi's mouth.

He checked the charge on the taser rod and secured it at his side. He kept the safety strap off. If he needed it, he would have to resort to the old fashioned quick draw style.

He waddled over to the tank entrance, and peered down into the water. A few fish were lazing around, but otherwise he could see nothing but the tank bottom.

Levi took a breath, and then placed the breather into his mouth as he sat down at the edge of the pool. He did one last check on his gear before quickly flipping backwards, his head breaching the cold water first.

He swam through this tank and every other tank in the facility a dozen times over. He often found that the cleaners did not accomplish their task to the degree that he would wish, so he knew every corner of this tank from top to bottom.

He made his way towards the far side of the exhibit, where the merman had been smashing into the glass. This tank had viewing spots on three sides, serving as one of the larger fish homes within the building.

Levi paddled quickly, and had reached the cracked spot before he knew it. The merman was gone.

It looked like he had made another pass at the glass during Levi's absence, but had not made nearly as much of an impact as he had the first time.

He could see Erwin, Hanji, and the others through the glass. Erwin had stepped up to the glass and was slapping his hand against the surface, shouting something, but the only sound that reached Levi was the dull thumps of his hand impacting the glass.

Levi shook his head, trying to tell Erwin that he had no idea what he was saying.

Suddenly Erwin's eyes widened and the blond man jabbed his finger into the glass in a panic. Too late did Levi realize that he was pointing to something in the water behind him.

Levi whipped around, just in time to see his attacker as he was rammed into the glass.

A green and gold tail thrashed in the water, drilling Levi into the glass, and strong arms squeezed his torso. He was being squeezed so tight that he was struggling to breathe. The merman released him, pulling away only to ram him into the glass once again.

Levi brought his hand to his side and grasped the hilt of the Taser rod. The merman pulled away once again, this time ratcheting his arm back to deliver a powerful punch. Levi glanced into his eyes, and saw gold tainting the bright, angry green.

The merman was furious, and rightly so. Levi would be pissed if he was dragged onto land in fishing net and trapped in a glass container that paled in size when compared to his natural home.

If this were any other situation, Levi would let the merman hit him; he would let him get his anger out. But Levi couldn't now. He was underwater, and if he let the merman beat him, then he would surely die here in this human attraction.

So, when the merman let his fist fly, fully charged with his rage, Levi whipped out the Taser rod and jabbed it into the merman's chest.

The merman screamed, and his body convulsed in the water as the electricity traveled through his body.

The merman went limp, his body falling still in the water. Levi breathed a sigh of relief. This was too much to deal with for one day. The fishermen should have just let the poor merman go. 

But they didn't, and now the merman was here, and Levi and his team were here, and everything was completely fucked up.

Levi made sure the merman was still alive and then assessed the damage on the glass. The crack was not as severe as he had thought. The glass was thick and strong, and the damage had not reached the outer layer. Good. Less trouble for Levi.

Erwin smiled in relief from the other side, and Hanji and the others had disappeared. They were most likely waiting at the entrance for him.

Levi glanced back at the merman and decided that he needed to be moved for now. The facility had several outdoor areas where they kept the Dolphins or other such animals that were being rehabilitated. Only trainers were allowed back there, and it was out of sight of the public. The merman could stay in there until they were sure he wouldn't try to break something else.

He grasped the merman's shoulders and pushed his body back to the tank entrance. When he reached it, he positioned him at the bottom of the tank under the entrance, and then swam up himself.

He surfaced, and Hanji and Petra were waiting for him.

"Are you okay?" Hanji asked, her glasses gleaming. "How's the merman? Did he say anything to you? What's he-"

"Hanji I don't have time for questions," Levi snapped, his irritation reaching a new level.

The scientist's glasses gleamed, but she said nothing else.

"Get a transport gurney; I don't want him in this tank. We're moving him to one of the outdoor areas.

Surprisingly enough, the scientist complied without any further inquiry. Petra gave Levi a relieved smile and followed after her.

Levi sighed and dived back down to retrieve the merman. Luckily he was still knocked out, but Levi was sure he would regain consciousness soon. 

He pushed the merman upwards, holding his body in place as he surfaced. Petra and Hanji were already there, along with Oulo, and they quickly slid the gurney into the water and under the merman. Oulo helped Levi lift from the back as they all worked together to get the merman out of the water.

Petra draped a water soaked cloth over the merman's neck, covering his gills. The water in the cloth would help the merman breathe long enough for them to transport him.

They all lifted the gurney together, and Levi was surprised at just how heavy the merman was. Levi kicked off the flippers, and his wet feet left a trail behind him as he walked.

They had just made it through the door when the merman began to stir, blinking his eyes in confusion. Hanji looked down at him and smiled, trying to comfort him as they slowly made their way down the stairs. 

It was tough going, as the merman's fish end was considerably heavier than his human torso. They struggled to make it to the bottom of the stairs, and when they did, they had to gently set the merman down to catch their breath.

Levi huffed, and Oulo cracked his neck as Hanji rolled her shoulders. The only down side to the plan was that that the access door to the outdoor facility was on the other side of the building, and the Merman was far too heavy to carry consistently for that distance. They would have to take multiple breaks.

"Hanji," Levi turned towards the scientist, clearly annoyed.

"Why didn't you take him to the outdoor facility in the first place?"

"Ah, well, when the captain and his crew showed up, they were in a big hurry to get rid of the merman, and I thought it would have been better to put him in a more familiar environment rather than into a rehabilitation area."

Levi quirked an eyebrow, but said nothing as they prepared to lift the gurney again. Levi had just grasped his side of the pole when the merman's tail suddenly began to writhe, slamming into Levi's ankles.

He went down, and Oulo and Petra rushed to hold the tail still. Levi picked himself up, clumsy with the tank still strapped to his back.

The merman's arms flailed, trying to find purchase on the slick tile floor. His hand grasped the towel draped over his neck, and he yelled something intelligible, clearly confused.

Hanji's eyes lit up with glee, and she quickly leaned down to speak with the confused merman. 

"Hey buddy! What's up!"

The merman yelled something at her, but none of them could tell what language he was speaking in.

"Ohhhh!" Hanji cried, her eyes sparkling in wonder.

"Your language is so beautiful. I wonder, can you sing as good as the legends say?"

The merman didn't respond, instead opting to snatch the glasses off of Hanji's face. Before anyone could stop him, he had broken the glasses like a twig, and was brandishing the broken metal at Oulo and Petra when they came too close.

Hanji didn't seem at all bothered by the merman's display of aggression, and instead took out a pen and notebook and scribbled something down.

"It's clear that your people have developed weapons of some sort, and that you are experienced in their use. Tell me, what advancements have you and your society made?" Hanji scooted closer to the merman, undeterred by the sharp object he was now wielding. Hanji was ready for his response, her pen poised over her paper in anticipation.

The merman's only answer was to stab Hanji in the hand.

The scientist screamed, quickly pulling away. The merman was about to make another slash, but Levi, who had seen enough, quickly batted it out of the merman's hand.

Hanji was still screaming, not from pain, but excitement. She was giggling as she pulled the metal from her hand, and Levi shivered. After today, he would have to put a restraining order on the scientist. He didn't want her anywhere near his house ever again.

Oulo and Petra grabbed the merman’s hands, trying to restrain him before he did anything else, and Levi was quick to pull out his Taser and prod the merman in the side. The Taser wasn’t on, but it was a warning.

Levi looked the merman dead in the eye, his thumb resting on the button to turn on the Taser. Everyone was still for a moment, waiting to see what he would do. Levi’s eyes never wavered from the merman’s, and finally the green eyes lowered, and the merman snatched his arms away to grasp his forearms.

Levi put the Taser away; still keeping his eyes trained on the merman’s every movement as they all moved to pick up the gurney once again. The merman keep his head angled down and his eyes closed, clearly trying to remove himself from his current situation.

After ten minutes of struggling to transport the merman, they made it outside and to an unoccupied pool. No one wanted to get in the water with the merman, afraid that he would regain some courage to strike out once he was back in the water, but their concerns were unneeded, as the merman simply turned himself over and threw all of his weight towards the pool. No one could stop him from sliding into the water, and none of them tried.

The merman splashed the water angrily, settling at the bottom of the pool to stare at them angrily. Petra and Oulo excused themselves immediately after, not wanting anything else to do with the merman for the rest of the day.

Hanji and Levi stayed for a little bit longer, making sure there was nothing near the pool that the merman could use to do something stupid. Hanji was enamored, watching the merman’s every movement and writing things down, muttering cryptically to herself.

Levi left her there, just as done with the whole situation as the others. Hanji would be keeping a very close eye on the Merman, and if it somehow killed her, then Levi wouldn’t necessarily consider that a loss.

Levi had to scoff at the whole situation. If they were smart, they would just go dump the merman in the ocean somewhere and act like this whole thing had never happened, but it was too late for that.

They were committed now, and something told Levi that the subject of their newest project would not cooperate with their efforts.

Fucking Fantastic.

**Notes for the Chapter:**

> Thanks for all the support already, it means a lot to me!


	3. Obviously Mermaids Can't Walk

**Summary for the Chapter:**

> Eren's a little shit and so is Hanji. Levi hates everyone.

**Notes for the Chapter:**

> Hey, well, I honestly don't know what to tell you guys. Its been months since I last updated, and all I can say is that I was busy. (also my laptop crashed and I had to get a new one). Nevertheless, I am back, and I will attempt to return to consistent posting, but I have never had a consistent posting schedule ever.  
> Sorry for the long A/N. Again I apologize for the late posting, but life tends to get in the way.  
> I should mention that most of the mermaids live in tribes, with a few exceptions. I went and edited the first chapter and it mentions some of these, so those of you who read the version before it was edited:  
> -Eren lives in a small hunting tribe that ferries goods between many of the larger tribes  
> -Individual families are known as clans  
> -There is a kind of mermaid capitol city in the Bermuda Triangle that is hostile to all outsiders, including other merfolk.  
> There's probably some other stuff that I forgot to mention, but you get the gist of it, leave a comment if you have any questions.

Eren really wished he had managed to cut that human’s fingers off. He really wished he had managed to drown that other one in the tank. He really wished he had killed the one that shoved him in that metal thing. He really wished he wasn’t a complete failure that got caught in a net. He really wanted to go home.  
After the humans removed him from the tiny cage he almost broke, they moved him into an even smaller one that was not as easy to break. He had already tried, and the nearly broken right hand was proof enough of that.

  
The humans had left him there the day before and he had seen none of them until that afternoon when one came to pull a net over the surface of the pool to keep Eren from jumping out. Sleep had not come easily that night, and he spent the better part of it nursing his fin and struggling to navigate through the water with only one working fin.  
A part of Eren recognized that his reduced physical mobility would have damned him if he had managed to make his escape when he was caught. It would have taken him the rest of the day and most of the night to reach the tribe, and then he, Mikasa, and Armin would have most likely been left behind because Eren would be too slow. He would never allow his own shortcomings to disadvantage his siblings, but they would never consider leaving him behind. His limited mobility would leave the three of them open to shark attacks, and he would never be able to live with himself if Armin of Mikasa got hurt of killed because of him. He ignored that side of himself, refusing to believe that his capture was fortunate in any way. There was strength in numbers, even if they were few. Besides, Eren had always been good in a fight, and he could grudgingly admit that Mikasa was as well. They would do fine on their own. They had before.

  
After his restless night passed and another human came and lifted the net, Eren had become increasingly curious about what was going on above the surface of the pool. He could feel sound vibrations in the water and occasionally noticed people passing by the pool. No one ever came to Eren’s pool, leaving the merman to himself. He resisted the urge to approach the surface, floating near the bottom where it was easy to avoid the rough, abrasive texture of the pool’s walls and keep his injured fin out of harm’s way. He was slightly grateful for the human’s avoidance, preferring to interact with them as little as possible.

  
The peace wouldn’t last for long.

  
Eventually, a shadow fell over the pool, shading Eren’s face from the sunlight that streamed through the bright blue water. It was that bug-eyed human from before, the one he stabbed. It had that creepy look on its face that Eren already knew meant trouble. He watched wearily as the human dragged up a bucket and fished around inside it. It pulled something out and tossed it into the water, warping the water’s surface and Eren’s view of the human.

  
The thing floated on the water’s surface, glittering brightly as it bobbed along. A smell reached Eren as a few more of the things were tossed in, and it was only the rumbling of his stomach in response that made him realize that he was staring at fish.

  
Food.

  
He eyed the human at the surface. It was sitting down now, well away from the water’s edge. Eren circled the bottom of the pool, testing his speed. He didn’t want to be near the surface if he could help it, but he was hungry, so he would try to reduce the time instead.

 

**********************

  
Hanji watched in avid interest as the merman circled the bottom of the pool, his movements hampered significantly by his missing fin. He was obviously planning to make a grab for the fish, and Hanji already had a camera rolling, ready to record the moment.

  
Surly enough, the merman breached the surface, his hands darting out to grasp the fish, his back arching as he quickly curved his body downward to re-enter the water. His tail splashed the water aggressively, flicking water onto Hanji intentionally as he disappeared below the surface. Hanji only giggled, saving the video to the memory card as she tossed more fish into the water.

  
The merman ignored the new morsels floating on the water and instead gulped down the first three, not even chewing the fish and instead swallowing them down, bones and all. Hanji watched, enraptured, as the merman’s neck seemed to expand and swell to accommodate the fish he swallowed down.

  
The merman made a few more passes at the surface, grabbing up the fish the same way each time, making sure to splash Hanji with water each time. She had made sure to keep away from the edge of the pool, for her own safety, but now that she thought about it, her distance probably made the merman feel safer to approach. She recorded her observations and new hypotheses in her notebook, and just as she tossed the last of her fish in the water, she got a _wonderful_ idea.

  
_Yes, it’s perfect_ , she thought.

  
Hanji made a show of rising from her spot and stretching, glancing at the merman out of the corner of her eye, who was in turn peering at her with clear suspicion. Hanji had to look away before a smile could break out on her lips.

  
_Can’t give it away, can’t give it away!_

  
Hanji picked up the bucket and deposited it with the others before checking the rest of the outdoor facility. None of the others were outside today, her plan could go into action immediately. Hanji quickly unlocked and opened the door to the indoor facility, leaving the door wide open. She also ‘accidentally’ dropped a cleaning rag on the ground near the Merman’s pool as she pretended to tidy up the area in case he or anyone else was watching. When she was satisfied her brilliant acting had made the merman lose interest, she pretended to walk back through the doors to the indoor facility, seemingly forgetting to close the door behind her.

  
She quickly dashed down the hallway and went through the side door, hopping over the fence so that she was back in the outdoor area. Hanji stalked quietly past the merman’s pool and wedged herself into a tight space between the wooden fence and the brick wall. No one else knew about her little hiding spot (except Levi, but he avoided her on principle), and it was the perfect place to observe the merman without him spotting her.

  
“Our meeting is going to be delayed Erwin. Sorry, not sorry,” she muttered, settling in to wait for as long as it would take for the merman to make his move.

  
**********************

  
Eren wasn’t the brightest tool in the shed, but he could hardly be blamed for assuming that it would be the perfect time to make an escape, despite the fact that he had no legs and couldn’t breathe for very long above water. Even if he could, he wouldn’t make it very far, but at the time, these concerns simply became technicalities. Who needs legs?  
He did, obviously.

  
He had been suspicious at first when bug-eyes (that’s what he decided to call the human) suddenly became very excited about something, scrambling to tidy up the surface area, most of which he couldn’t see due to his lower position in the water. He listened intently for several minutes until silence suddenly befell the area, and that’s when Eren knew he was totally alone in this place.

  
It had been a tentative moment when he stuck his head out of the water and peered over the pool’s concrete edge. There wasn’t a single human in sight.  
It seemed too good to be true, and Eren was tense as he waited for a human to come walking through the open door of the building across from him. None ever did.  
Eren’s eyes darted about the area once again before he finally grit his teeth and made a go for it.

  
Hauling his body up out of the pool was far more difficult than it needed to be, but with a missing fin, there wasn’t much Eren could do to boost his momentum to give himself the extra push to get his lower body over the edge. After a lot of huffing and puffing and three re-starts, Eren managed to get his entire body onto the concrete. He immediately began feeling the effects of suffocation on his body, and he was quick to snatch up a discarded rag and dip it in the water and drape the wet rag over his gills. The humans had done the same thing yesterday when transporting him, and it seemed to work just fine.

  
With the breathing problem solved he immediately selected the exit for his desired escape attempt: the wide open doors of the indoor facilities. He hoped that there were no humans in there either, but the chance of that was minimal. That was a problem. If he was caught, they would drag him right back to the pool, and they would probably keep that net over the water to make sure he would never escape again.

  
He needed a weapon.

  
An immediate scan of the area yielded no suitable candidates that could at least be broken to form some sort of crude weapon, and Eren was forced to pull his body across the rough concrete to conduct a more thorough search. He eventually got his hands on a metal skewer that had been attached to a pole. It wasn't much, but it would have to do.  
Eren soaked his breathing rag in the pool again before he set off, slowly dragging his heavy tail onto the smooth tile of the indoor facility. Eren was still soaked, and the water helped him glide his body over the smooth floor easily.

The building wasn't the same one the human's had carried him out of yesterday. He had been kept in the building on the other side of outdoor area that housed his pool. The building he was in now was most likely some sort of management facility and had less decoration that the other building. The halls were lined with offices and the walls were painted a plain white color, but Eren didn’t notice any of that. He noticed door at the end of the hallway that undoubtedly led to the outside. Eren didn’t hesitate as he began pulling himself down the narrow hallway. He didn’t think about what he would do once he got though those doors. There was only one word on his mind.

Escape.

**********

            Levi hadn’t wanted to deal with the merman after they finished relocating him. He didn’t even want to acknowledge the merman’s existence. After he made sure Hanji wouldn’t die from her injury, he cleaned up the water trail they had created when they moved the merman. Then he procrastinated the conversation with Erwin that he knew was coming by cleaning out the fish tanks and exhibits. And then he reorganized the filing cabinets. And then he made calls to arrange getting the fish and living corals out of the cracked tank in order to drain the water and replace the glass. And then he went out for lunch and nearly ran into Erwin at the burger joint down the street. He didn’t want to talk to the blond because he knew what he would say.

He obviously wanted Levi to head the process of rehabilitating the Merman and become his head “trainer.” He doubted that the merman would appreciate having a trainer in general, much less Levi. He wouldn’t be able to avoid Erwin forever, as he had undoubtedly noticed Levi’s avoidance, but Levi didn’t see head of tail of Erwin for the rest of the day. The fact that the blonde had not sought him out made Levi slightly nervous, and when he left the Research Center at the end of the day he half expected Erwin to randomly pop up out of the sidewalk.

But he never did.

Levi went to bed that night feeling restless, trying to figure out how he was going to meet the unspoken challenge that Erwin had proposed. He didn’t want to deal with any of this, but Erwin had backed him into a corner, and it was only then that Levi realized that he probably hadn’t seen Erwin for a reason. If Erwin had wanted to speak to him he would have found a way, even if he had to wait in Levi’s driveway for him to come home. He had done it before, and Levi wouldn’t put it past him to do it again.

He was leaving the next step up to Levi, trusting him to make the right decision, and that was almost as nerve wracking as the fact that there was a live merman living in the rehabilitation pool. He would never admit it, but he really respected Erwin, and letting the man down would be worse than losing an arm.

When he came into work the next day, he still wasn’t ready to approach the merman, so he left the job of feeding him to Hanji, which made her giddy with excitement. He swapped jobs with Oulo and Petra all day, now avoiding the merman rather than Erwin. Hanji had a meeting scheduled with Erwin, so he would wait until the scientist was out of the way to make a move.

But of course Hanji had to go missing.

She had never returned from her mission to feed the merman, and Levi was seriously concerned that she had been drowned. After fussing around with the pamphlets at the front counter and getting shooed of by Petra, he couldn’t put it off any longer, so it was with great reluctance that he made his way to the outdoor facility. He was slightly surprised to see that Hanji was not outside with the merman.

He was even more surprised to find that the merman wasn’t outside either.

_Oh fuck, Hanji, what did you do?_

The merman was gone and Hanji was nowhere in sight. His eyes landed on a fading water trail that led to the management facility. Levi followed it, already planning the ultimate chewing out speech for Hanji. He didn’t know how the merman got out, but Hanji definitely had something to do with it.

He stopped in the doorway when he saw the merman attempting to break the glass on the front door. He was clearly struggling to hold up his torso while simultaneously trying to punch through the glass. He had a soaked rag thrown over his gills and there was a piece of metal sitting on the tile floor.

The merman hadn’t noticed him yet, and Levi crouched down and silently padded forward. He needed to get that weapon away from the merman, and he prayed that the merman would be too distracted to sense his approach until he got ahold of the weapon.

Levi was right behind the merman, carefully reaching up to snatch the metal skewer away. He held his breath as he deftly pulled it away, slipping it into his pocket. The merman was oblivious, pounding his fist on the glass in frustration. He was clearly exhausted, breathing heavily as he allowed his body to sag to rest for a moment. He wasn’t used to moving around outside of the water, and the energy he needed to escape had left him after all the strain of moving his body around on land.

Levi moved away from the merman and tried to assess the situation. He should call for help. Now that the merman’s weapon was gone, it would be easy to surround him and corral him back into the pool. He was about to make a call into the radio at his side when the merman backed himself up, laying down to rest. The merman was still, save for his back raising up and down as his breathing settled. The merman couldn’t see him from where he was, but Levi could see his face, and what he saw there made him feel guilty.

Those bright green eyes looked angry and full of fire, but there was something underneath them, a desperation that made Levi pause. He watched as the merman closed his eyes, his frustrated face softening as he seemed to make a decision.

When he opened his eyes there was a look of defeat in them that Levi felt was very out of place in those bright green oceans. But the fire was still there, burning just underneath the surface. Levi slipped into one of the offices, peeking through the blinds of the glass window to watch as the merman somehow managed to turn himself around and get back down the hallway, not noticing the missing skewer.

Levi left the office and followed behind as the merman dragged himself back to the edge of the pool and slipped back into the water. The merman reached his arm up a moment later to deposit the rag at the edge of the pool and never resurfaced after that.

Levi sighed and closed the door of the facility, locking it for good measure and making a mental note to clean up the mess the merman had made later.

He would come back to check on the merman later. For now he needed to find Hanji and give her that speech.

**Notes for the Chapter:**

> I'm really going to try and post another chapter soon. Thanks for reading!


	4. One Step Forward (And Two Steps Back)

**Summary for the Chapter:**

> Levi gets over himself, we check back in with the fam, and Eren gets to be a badass.

**Notes for the Chapter:**

> So.... Yeah, I really don't have an excuse for why this is so late. I could tell you all the reasons, but many are personal, or unimportant, and I don't want to bore you with the details. Many apologies, I'll try to be better.  
> *bows  
> Anyways, let's just get on with it, I know you guy's have been waiting.  
> If you have any questions just leave a comment!

There was a lot that Mikasa was willing to deal with, something that Armin knew well. She could take a lot of shit, all because she wanted to protect him and Eren. She was possessive by nature, yet willing to give up everything as long as they all stuck together. She could do anything as long as she was sure that her efforts were to their advantage.

After more than a week of searching for Eren, she wasn’t the same.

At first she had been calm, so had he. They were sure that Eren was just running late, even when he didn’t show up for dinner that first night. Even when he and Mikasa stayed up all night waiting for him.

Mikasa was calm all through the next day and that night.

She was calm as the tribe went through the hustle and bustle of packing everything away so that they could begin moving on the next morning.

It was that morning that she finally broke. She had been frantic, swimming far out beyond the tribe’s borders to search. Armin went with her, but somehow he knew they wouldn’t find Eren.

He didn’t want to think about where Eren could be.

He suggested to Mikasa that Eren may have moved on to the next tribe ahead of them. He had had to do that a few times when he found artifacts that he couldn’t easily hide, and had to sell them quickly so as not to raise any suspicion.

Mikasa calmed down considerably after that, and she and Armin moved to the front of the travel group. Armin guessed it made her feel better to be even just a little ahead of everyone else without just shooting off into the ocean without help.

They didn’t find Eren at the next tribe.

He didn’t suddenly appear, laughing, asking why they left him behind.

Eren was gone.

****

Mikasa liked to think that maybe Eren was eaten by a shark; that if he was dead, he died quickly. She didn’t want to think that he had been sucked into a seabed hydrogen vent and boiled to death. She didn’t want to think that he got tangled up in an abandoned human fishing net and dragged down into a trench, never to see the light again.

She wished that he were dead, because if he was alive he would be suffering. She wished he was dead because it would be foolish of her to wish him to be alive and here with her and Armin. The world didn’t work like that. This world was cruel, and it took from her everything that she held dear.

_Mom..._

_Dad…_

_Carula…_

_Grisha…_

_……Eren._

_Because of this cursed blood of mine…_

She needed to leave. She needed to disappear before someone else did. Armin was at risk because he continued to stay by her. He would die if she continued to be selfish, if she continued to seek out that which she was not meant to have.

She knew better, yet still she….

Armin was weak. He wouldn’t do well on his own. He would be lonely. He would look for her. She shook those thoughts out of her head. He would be all alone if she left, but the tribe would take care of him. A clan would adopt him, just as the Jaeger clan had done for her. He would be safe.

If she stayed he would be dead.

Approximately a week and six days after Eren’s disappearance, she disappeared from the tribe. She didn’t look back as she swam away. She was resolved. If she looked back she would lose her nerve. She didn’t look back. She looked ahead and forced the image of Armin’s disappointed face away from her mind.

No one else would die because of her.

*****

When Levi finally tracked down Hanji, it was the next day, and she was watching footage of the merman on her computer in her office of the management facility. She wasn’t aware of his presence yet, and Levi realized she was watching footage of the merman’s aborted escape yesterday.

It took Levi only a moment to realize that Hanji had witnessed the whole thing, filming it from her stupid hiding spot between the fence and the public facility.

Levi abruptly made his presence known by slamming his palm onto the desk.

“You’ve got a lot of explaining to do Shitty Glasses.”

“Ah, Levi, you’re just in time!” Hanji was completely immune to Levi’s glare, or if she wasn't, she was really good at hiding it. He pretended like it didn’t bother him.

“Care to explain this?” Levi asked, already fed up with her nonchalance.

“Certainly,” she quipped, spinning her chair in a circle so that Levi could see the screen better.

“I took it upon myself to estimate the Merman’s intelligence by introducing a very basic, yet tempting, scenario. I want to know what we’re going to be working with in terms of overall intelligence and cognitive understanding.”

Her eyes suddenly took on a dangerous gleam, and she began rubbing her hands together.

“The results were better than I had ever hoped. Casus has displayed amazing-“

“What?” Levi wasn’t sure he heard her right. Casus? Had she named the merman already?

“What’s wrong?” Hanji asked, genuinely confused.

“Hanji, we can’t go naming this thing yet, we haven’t even decided if we’re keeping it.”

Hanji deflated instantly.

“But I have so many tests that I want to do! Do you know how exciting this is Levi? Casus is literally the gateway into a whole other world. He can teach us about a society that has only ever been the stuff of conjecture and fantasy!”

Levi could feel his headache coming on already.

“Hanji, we need to slow down and think through this rationally. I understand your excitement, but I think it would be a lot better for everyone if we just patch him up and take him back to where he was found.”

Hanji looked frustrated now, no, more than frustrated, angry.

Levi took a step back, all of a sudden very nervous, and very aware he was trapped in an enclosed space with a kleptomaniac who was the star of her wrestling team in high school. Levi was no pushover, but crazy people weren’t either if they weren’t strapped to a chair.

“And what will that do for him in the long term Levi? If we take him back to where we found him, we could possibly drop him into waters that are not as hospitable as they were before. You and I both know that his people, if he has any, are probably nomadic, and that they either migrate with the seasons to escape the turmoil caused by storms and rising or falling temperatures, or follow some other strange logic that we have no way of knowing about. The same waters that were free of predators in the spring can be infested with sharks by winter. We have no idea how he operates, intellectually or biologically.”

Hanji whipped off her glasses, rubbing the filthy lenses on her greasy shirt. They were most likely smudged and streaked when she put them back on, and if they were, she didn’t seem to notice. She wasn’t done with Levi yet.

“I know sometimes you forget, but you’re a scientist too, Levi. It might sound cruel of me to say so, but you need to stop thinking of Casus as a person and more of an animal. He may look human, but we know nothing about him. I’m trying to get at least a basic understanding of how Casus thinks. He’s as intelligent as you and I, possibly more, but we can’t know until everyone else around here decides to get their thumbs out of their asses and starts working.”

And with that, Hanji pushed Levi out of the room and slammed the door in his face. He didn’t react at all, still reeling from the verbal shake down Hanji had just delivered.

How did he get to this point, when the last person Levi would expect to receive a verbal thrashing from does just that.

Her words spun through his head, and he couldn’t help but replay the whole interaction back in head as he stepped back from the door to lean against the opposite wall.

Everything Hanji said was right. Just when had Levi begun to think of the Merman as human? Probably the moment it tried to kill him in that tank, brilliant green eyes tinted gold with rage, an all too human emotion that Levi was very familiar with. He had no doubt that the Merman, Casus, as Hanji was calling him, was somewhat human, but Hanji didn’t mean that he wasn’t. In the end, they were still scientists and marine biologists, and, in Levi’s case, veterinarians. They needed to approach this as if they were handling an injured dolphin, or turtle, or anything else. Levi specialized in aquatic mammal trauma care, so he needed to put this in the actual realm of his job and not get tangled up in the details. Hanji was good at handling all of that. That’s what she was doing right now.

And Levi was just standing around and whining like an asshole kid.

God-damnit, he hated it when she was right.

“Well I was coming to chew you out, but it seems that Hanji beat me to it.”

Levi opened his eyes (when had he closed them?) to see Erwin standing in the front door of the management facility.

Levi rolled his eyes, not ready to deal with Erwin after everything with Hanji just now. But he was never really ready to deal with Erwin.

“Don’t you get started in me too,” he said, turning his back to walk out the back door into the outdoor facilities.

“Hold on Levi. Since I’m here I think I might as well formally assign you to your new patient.”

Levi stopped in the doorway. He knew this was inevitable. He would be solely responsible for the rehabilitation and release (hopefully) of the merman.

There was no point in fighting Erwin about it. Once that man made up his mind, nothing could sway him. Levi loved and hated him for that.

So Levi only sighed and continued out through the door, leaving Erwin with only the words, “I want a raise.”

*****

Rehabilitation began that afternoon. Hanji had already gotten a good feel for the Merman’s eating habits, having fed him multiple times already. Hanji had a rather detailed log explaining her feeding process. She first fed Casus mackerel, and then tested his preferences based on the diets they usually constructed for their other marine mammals. Casus would eat everything except clams, and she wasn’t sure whether it was because of actual dietary concerns or a dislike for the food. Levi decided to feed Casus Mackerel again, supplemented with cod fillets and some herring.

Hanji also stated in her log that the merman was overly cautious when people came near the pool, and only dared to grab fish from the water's surface when Hanji was well away from the pool, or gone altogether. Levi would have to change that.

When Levi approached the pool, bucket of stinking fish in hand, the merman was making slow circles around the pool’s bottom. Somehow, the merman sensed his approach and immediately went on the defensive, awkwardly fluttering into the far corner of the pool, green eyes locked firmly on Levi.

Levi pretended not to notice, setting the bucket down well away from the pool’s edge. Petra was with him, but she stayed out of the merman’s field of view. In order to begin Casus’ rehabilitation they needed to get a good look at his wound, and going in the water with the merman was definitely not an option. Understandably, the merman would also not want to come out, so Levi was going to have to find some way to get across to Casus that he really didn’t have a choice in the matter.

He would try diplomacy first, and brute force later. Levi had a taser rod strapped to his thigh in plain view so the merman knew not to try anything, but Petra had a taser rod and a tranquilizer gun at the ready, just in case. Levi hoped they wouldn’t need them. Hanji had to make a few guesses about the dosage of the tranquilizer, as we had no idea how much it would take to take the merman down. Hanji did some guesswork based on what they had seen of the Merman’s size, and they all crossed their fingers that the tranquilizers would be strong enough to at least slow the merman down, but not be strong enough to kill him. That being said, the tranquilizers were a last resort.

Once she signaled she was ready, Levi lowered himself to the edge of the pool, eyes locked on Casus, even as the merman stared back, challenging. Once Levi settled at the edge, he dangled his legs over the edge, toes dipping into the water. He tried to appear relaxed, but his whole body was humming with tension, ready to bolt should the merman make a move.

He stared at the merman a moment longer, and then quickly broke eye contact in order to grab the bucket and drag it over. The merman remained in his place in the far corner, unmoving, save for the flaring of his gills as he breathed.

Levi made eye contact with the merman again, pulling a cod fillet out of the bucket and plopping it into the water by his feet. The fillet floated across the water’s surface, jerking around from the rapidly calming ripples of its impact.

The look on the merman’s face was almost annoyed, and Levi made a point of pushing the bucket out of sight. His message was clear.

_You come up here, or you don’t eat._

Casus wasn’t happy with those terms, to say the least.

He bared his teeth, sharp incisors glistening in the light. His whole body seemed to puff out, his fins spreading and arching as far as they could, green and gold flukes that had previously melded with his skin spreading on his forearms, waist, and jaw. The display was intimidating, as Levi was sure it was meant to be. The only warning he got before the merman charged was the sudden flash of flesh under the merman’s gills as he exhaled, then inhaled.

Levi scrambled away from the pool’s edge, feet barely clearing the water before the merman was there, snapping at his toes. The merman’s momentum had sprung him out of the pool and onto the concrete. The only part of the merman left in the water was the back section of his tail.

The merman hissed, not seeming at all put off by the lack of a proper breathing atmosphere.

Levi backed away. And Petra was there, pointing the tranq-gun at the merman’s chest.

Levi held out his hand for her to hold, unsure of the merman’s intentions. The plan had totally gone to shit, but he could still try and salvage the situation. Diplomacy before violence.

The merman stared them down, either unconcerned about the weapons they held or unaware of the actual danger he was in.

Levi and Petra were frozen. They held the advantage, having both weapons and biological superiority on land, but somehow, Levi didn’t feel safe.

Casus stared them down, his flukes slowly falling and melding back into his skin, the vibrant color fading. The merman lifted the last of his tale out of the water, and Levi go a good look at the wounded fin for the first time.

Compared to the other one, there was hardly nothing left of it. It had been sheared off like wool from a sheep, but Levi had no idea if it would grow back or not. There wasn’t much damage to the tail area surrounding the fin, save for patches of missing scales, which revealed raw, pink flesh underneath.

Casus shifted his tale, and the injured one left Levi’s view. Casus still stared at him, but Levi could sense that his aggression was waning. Casus couldn’t stay up here for much longer, but he seemed satisfied that he had made his point.

Before he or Petra could do or say anything, the merman dived back into the water, his tail whipping out to knock the bucket and its contents into the pool.

Levi and Petra watched at the merman collected his prize, pecking up the fish from underneath the water’s surface.

Levi could have sworn that the little shit smiled, smug as a skunk in a tight space.

“Damn it…” Levi sighed. This wasn’t exactly how he wanted the first day to go, and there was no point in trying to continue. They no longer had any leverage to convince the merman to cooperate. They would just have to wait until tomorrow.  
Petra walked towards the main facility doors to take the tranq gun back inside. She didn’t say anything, having worked with Levi long enough to know he was in no mood for talking. There was nothing to talk about.  
The merman eyed him from the bottom of the pool, his neck expanding as he swallowed a fish whole. His gaze was challenging, his movements lazy, as if moving like he just had had taken no energy at all. In normal circumstances Levi would say it hadn’t. But the merman was injured and off balance. If he was at all tired from his stunt just now, he didn’t show it.  
Levi grabbed a pool net and fished the bucket out of the pool, wearily watching the merman the whole time, who made no move to intervene.  
Just to make it look like he was still working (because Erwin was probably watching, somehow) he tidied up the area and made his rounds to feed a few of the other animals in the rehabilitation area. A pert of Levi’s brain was focused on the merman still, planning out his approach for tomorrow.  
Levi had wanted to begin building some kind of trust with the merman before they began the necessary steps to check on Casus’ health, but the merman was uncooperative, to say the least. For both scientific and health purposes, they needed to do a full medical rundown to make sure there weren’t more problems with the merman than what was obvious. Dieting plans needed to be made, medical records recorded, along with behavior logs, psychological assessments, language and intelligence tests, and about a billion other things that Levi and Hanji had to manage basically on their own. Animals are, in their own way, people, but were way easier to understand and had simpler agendas and needs. Actual people, humans, were complex, complicated, and messy, and Casus was a mix of the two. Levi was good at handling only one side, not the other. Neither he nor Hanji had ever dealt with something like this before. Hanji was a scientist, through and through, and, while she wasn’t necessarily a people person, she was good at picking them apart and getting to know them on s creepy, psychological level.  
For Levi, animals had always been easier to understand. In layman’s terms, they only worried about eating, sleeping, and shitting. Levi could take care of those first two things easily, and the third grudgingly, so going a step further and ensuring actual survival in times of trouble was only a little bit more difficult.  
But Casus was different than all of that, and if Hanji or Levi made a mistake, the effects could be permanent, shocking, or even deadly for one or all of them.  
The part of Levi that acknowledged that wanted to take the next few days slowly and give the merman time to adjust, and to earn a bit of his trust. But the professional, medical side of himself said that if he wanted to help this merman he might have to be a bit cruel first.  
So he made his decision. Tomorrow, they needed to begin collecting Casus’ medical data, and if they had to, Levi would risk the tranquilizers tomorrow. They most likely would end up using them, so Levi spent the rest of the afternoon organizing the logistics of it, getting equipment moved, documents ready, and trusted employees on staff.  
Tomorrow was going to be hell.

**Notes for the Chapter:**

> There will be more story with Mikasa coming up soon. That's actually part of the reason this has taken so long. I've been painstakingly writing out a very detailed plot, discovering holes, and coming back to fill them. It's all been a very long process that I think will produce something you'll all enjoy. The next few chapters are going to be building momentum into the main plot, which is not what you think it is.  
> Lol, I have so much planned!


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